49
The soft stop amps threshold function can be terminated and
the compressor motor deenergized immediately by depressing
the STOP button twice.
Chilled Water Recycle Mode —
The chiller may
cycle off and wait until the load increases to restart when the
compressor is running in a lightly loaded condition. This cy-
cling is normal and is known as “recycle.” A recycle shutdown
is initiated when any of the following conditions are true:
• the chiller is in LCW control, the difference between the
LEAVING CHILLED WATER
temperature and
ENTER-
ING CHILLED WATER
temperature is less than the
RECYCLE SHUTDOWN DELTA T
(found in the
SETUP1 table)
and
the
LEAVING CHILLED WATER
temperature is below the
CONTROL POINT
, –5 F
(–15.0 C) the
CONTROL POINT
has not increased in the
last 5 minutes and ICE BUILD is not active.
•the
ECW CONTROL OPTION
is enabled, the difference
between the
ENTERING CHILLED WATER
temperature
and the
LEAVING CHILLED WATER
temperature is less
than the
RECYCLE SHUTDOWN DELTA T
(found in
the SETUP1 table), and the
ENTERING CHILLED
WATER
temperature is below the
CONTROL POINT
–5 F (–15.0 C) and the
CONTROL POINT
has not
increased in the last 5 minutes.
•the
LEAVING CHILLED WATER
temperature is within
3º F (2º C) of the
EVAP REFRIG TRIPPOINT
.
When the chiller is in RECYCLE mode, the chilled water
pump relay remains energized so the chilled water temper-
ature can be monitored for increasing load. The recycle control
uses
RECYCLE RESTART DELTA T
to check when the com-
pressor should be restarted. This is an operator-configured
function which defaults to 5º F (3º C). This value can be
viewed or modified on the SETUP1 table. The compressor will
restart when the chiller is:
• in LCW CONTROL and the
LEAVING CHILLED
WATER
temperature is greater than the
CONTROL
POINT
plus the
RECYCLE RESTART DELTA T
.
• in ECW CONTROL and the
ENTERING CHILLED
WATER
temperature is greater than the
CONTROL
POINT
plus the
RECYCLE RESTART DELTA T
.
Once these conditions are met, the compressor initiates a
start-up with a normal start-up sequence.
An alert condition may be generated if 5 or more recycle
start-ups occur in less than 4 hours. Excessive recycling can re-
duce chiller life; therefore, compressor recycling due to ex-
tremely low loads should be reduced.
To reduce compressor recycling, use the time schedule to
shut the chiller down during known low load operation period,
or increase the chiller load by running the fan systems. If the
hot gas bypass is installed, adjust the values to ensure that hot
gas is energized during light load conditions. Increase the
RECYCLE RESTART DELTA T
on the SETUP1 table to
lengthen the time between restarts.
The chiller should not be operated below design minimum
load without a hot gas bypass installed.
Safety Shutdown —
A safety shutdown is identical to a
manual shutdown with the exception that, during a safety
shutdown, the CVC displays the reason for the shutdown, the
alarm light blinks continuously, and the spare alarm contacts
are energized.
After a safety shutdown, the softkey must be
pressed to clear the alarm. If the alarm condition is still present,
the alarm light continues to blink. Once the alarm is cleared,
the operator must press the or softkeys to re-
start the chiller.
BEFORE INITIAL START-UP
Job Data Required
• list of applicable design temperatures and pressures
(product data submittal)
• chiller certified prints
• starting equipment details and wiring diagrams
• diagrams and instructions for special controls or options
• 23XL Installation Instructions
• pumpout unit instructions
Equipment Required
• mechanic’s tools (refrigeration)
• digital volt-ohmmeter (DVM)
• clamp-on ammeter
• electronic leak detector
• absolute pressure manometer or wet-bulb vacuum indi-
cator (Fig. 30)
• 500-v insulation tester (megohmmeter) for compressor
motors with nameplate voltage of 600 v or less, or a
5000-v insulation tester for compressor motor rated
above 600 v
Using the Optional Storage Tank and Pump-
out System —
Refer to Chillers with Storage Tanks sec-
tion, page 71 for pumpout system preparation, refrigerant
transfer, and chiller evacuation.
Remove Shipping Packaging —
Remove any pack-
aging material from the control center, power panel, motor
cooling and oil reclaim solenoids, motor and bearing tempera-
ture sensor covers, and the factory-mounted starter.
Open Oil Circuit Valves —
Check to ensure the oil fil-
ter isolation valves (Fig. 3 and 4) are open by removing the
valve cap and checking the valve stem.
Tighten All Gasketed Joints —
Gaskets normal-
ly relax by the time the chiller arrives at the jobsite. Tighten all
gasketed joints to ensure a leak-tight chiller.
Check Chiller Tightness —
Figure 31 outlines the
proper sequence and procedures for leak testing.
23XL chillers are shipped with a full refrigerant and oil
charge. Units may be ordered with the refrigerant shipped sepa-
rately, and a 15 psig (103 kPa) nitrogen-holding charge in each
vessel. To determine if there are any leaks, the chiller should be
charged with a refrigerant tracer. Use an electronic leak detec-
tor to check all flanges and solder joints after the chiller is
pressurized. If any leaks are detected, follow the leak test
procedure.
If the chiller is spring isolated, keep all springs blocked in
both directions to prevent possible piping stress and dam-age
during the transfer of refrigerant from vessel to vessel during
the leak test process, or any time refrigerant is being trans-
ferred. Adjust the springs when the refrigerant is in operating
condition and the water circuits are full.
Refrigerant Tracer —
Carrier recommends the use of an
environmentally acceptable refrigerant tracer for leak testing
with an electronic detector or halide torch.
Ultrasonic leak detectors can also be used if the chiller is
under pressure.
RESET
CCN LOCAL
Do not use air or oxygen as a means of pressurizing
the chiller. Mixtures of HFC-134a and air can undergo
combustion.
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